Highly sensitive electrochemiluminescence detection of p53 protein using functionalized Ru-silica nanoporous@gold nanocomposite

A simple, rapid response time and ultrahigh sensitive electrochemiluminescence (ECL) immunosensor based on Ru(bpy)32+doped silica doped AuNPs (Ru-Si@Au nanocomposite) was developed for detection of p53 protein, a well-known tumor suppressor. The immunosensor was constructed using biotinylated capture antibody, immobilized on the glassy carbon electrode (GCE) using streptavidin modified-gold nanoparticles/thiolated graphene oxide, followed by its conjugation with the Ru-silica@Au nanocomposite labeled secondary antibody to form a sandwich-type immunocomplex. The use of Ru-Si@Au nanocomposites led to a remarkable increase in the ECL intensity and, thus, the sensitivity of the method. Under the optimized conditions, the linear range of the proposed p53 immunosensor was found between 0.2 and 200 pM with a calculated limit of detection of 22.8 fM. The selectivity and reproducibility of the immunosensor was also investigated and the results showed high specificity and great stability in detecting of p53. Moreover, the ECL immunosensor was successfully applied for quantification of p53 protein in the human spiked serum samples and more importantly in the human normal and cancer skin fibroblast cells showing much satisfactory result compared with the ELISA method. The proposed immunosensor reported herein offers a considerable potential in early detection of cancer and clinical diagnosis and provides a new platform for biomarker detection.